docs: def get_eci_assignment_number(encoding):
      """\
      Returns the ECI number for the provided encoding.
  
      :param str encoding: A encoding name
      :return str: The ECI number.
      """
      try:
          return consts.ECI_ASSIGNMENT_NUM[codecs.lookup(encoding).name]
      except KeyError:
          raise QRCodeError('Unknown ECI assignment number for encoding "{0}".'
                            .format(encoding))